Cannabis sativa, in the form of marihuana or hashish, is perhaps the most widely used illicit psychoactive drug in the world. Controversy about its pharmacological effects and potential for harm has prompted a flood of research in the past decade [1ߝ3]. In spite of this concentrated research effort the metabolism of the active constituents of Cannabis is incompletely elucidated, and analytical methods to supply hard chemical information about marihuana ingestion for both forensic and pharmacological purposes are woefully lacking.